Electromagnetic brake control circuitry for elevator application

ABSTRACT

A brake system for an elevator car includes a multiple of brake segments for deceleration of the elevator car and a brake control circuit operable to control operation of each of the multiple of brake segments to passively sequence activation of each of the multiple of brake segments.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of provisional application Ser. No.62/185,827, filed Jun. 29, 2015.

BACKGROUND

The present disclosure relates to an elevator system and, moreparticularly, to elevator systems equipped with an electromagnetic brakesystem.

In emergency stop (E-stop) operation such as during power interruptions,engagement of an electromagnetic brake system may result in passengerdiscomfort due to the abrupt deceleration. This may be particularlynoticeable in a downward travelling elevator car, with the car beinglighter than the counterweight (motoring run), when the brake forces andgravitational forces are in the same direction. Regulatory bodies haverestricted the performance of electromagnetic brake systems to addressthese conditions.

In conventional roped elevator systems, the rate of deceleration isrelatively low due to the relatively heavier cars, counterweights, andresultant drive machine inertia. In relatively more recent elevatorsystems, the elevator cars are much lighter and the overall systeminertia is lower, which contributes to relatively higher rates ofdeceleration during an emergency stop event. This relatively high rateof deceleration may also result in belt slippage, which may beunacceptable under certain regulatory regimes.

SUMMARY

A brake system for an elevator car according to one disclosednon-limiting embodiment of the present disclosure can include a multipleof brake segments for deceleration of the elevator car; and a brakecontrol circuit operable to control operation of each of the multiple ofbrake segments to passively sequence activation of each of the multipleof brake segments.

A further embodiment of the present disclosure may include, wherein thebrake control circuit includes an electromagnetic coil and a snubbernetwork for each of the multiple of brake segments.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network for each of the multiple ofbrake segments control a sequence to control the deceleration of theelevator car.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network includes a diode.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network includes a Zener diode.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network includes a resistor in serieswith a diode.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network includes a capacitor inparallel with a diode.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the snubber network includes a coil in series witha diode.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein stopping a flow of electrical current through thebrake control circuit is operable to initiate engagement of theelectromagnetic brake.

A brake system for an elevator car according to another disclosednon-limiting embodiment of the present disclosure can include a firstbrake segment operable to apply a first brake torque at a first time inresponse to a first snubber network; a second brake segment sequentiallyoperable subsequent to the first brake segment in response to a secondsnubber network, the second brake segment operable to apply a secondbrake torque at a second time subsequent to the first time; and a thirdbrake segment sequentially operable subsequent to the second brakesegment in response to a third snubber network, the third brake segmentoperable to apply a third brake torque at a third time.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the third time is subsequent to the second time.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the third time is about equal to the second time.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the first, the second, and the third brake segmentare sequentially operated to stop 125% of a rated load of the elevatorcar.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein two of the first, the second, and the third brakesegments are operable to stop 100% of the rated load of the elevatorcar.

A method of engaging an electromagnetic brake for an elevator systemaccording to another disclosed non-limiting embodiment of the presentdisclosure can include sequentially controlling application of amultiple of brake segments for deceleration of the elevator car inresponse to the stopping of a flow of electrical current through a brakecontrol circuit.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein sequentially controlling application of each of themultiple of brake segments includes controlling a response time of eachof the multiple of brake segments.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein controlling the response time of each of themultiple of brake segments is effectuated by a snubber network.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the brake control circuit is passive.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the brake control circuit includes anelectromagnetic coil and a snubber network for each of the multiple ofbrake segments.

A further embodiment of any of the embodiments of the present disclosuremay include, wherein the response time of each of the multiple of brakesegments is determined by the snubber network.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be appreciated, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art fromthe following detailed description of the disclosed non-limitingembodiment. The drawings that accompany the detailed description can bebriefly described as follows:

FIG. 1 is a schematic view of an embodiment of an elevator systemaccording to one disclosed non-limiting embodiment;

FIG. 2 is a schematic view of forces acting on an embodiment of anelevator system under a regenerating run;

FIG. 3 is a schematic view of forces acting on an embodiment of anelevator system under a motoring run;

FIG. 4 is a schematic view of an electromagnetic brake for an elevatorsystem;

FIG. 5 is a chart illustrating relationships for example electromagneticbrake systems with multiple segments;

FIG. 6 is a schematic view of another embodiment of an electromagneticbrake for an elevator system;

FIG. 7 is a schematic view of still another electromagnetic brakeembodiment of a braking system for an elevator system;

FIG. 8 is a graphical representation of example operational values forthe FIG. 7 braking system;

FIG. 9 is a schematic view of still another electromagnetic brakeembodiment of a braking system for an elevator system;

FIG. 10 is a graphical representation of example operational values forthe FIG. 9 braking system;

FIG. 11 is a schematic diagram of a braking control circuit for anelevator system; and

FIG. 12-16 are schematic diagrams of a portion of alternate brakingcontrol circuits for an elevator system.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an elevator system 10. The elevatorsystem 10 includes an elevator car 12 located in a hoistway 14. Thehoistway 14 includes one or more guide rails 16 interactive with one ormore guide shoes 18 of the elevator car 12 to guide the elevator car 12along the hoistway 14. A suspension member 20, typically a rope and/or abelt, suspends the elevator car 12 in the hoistway 14. It should beappreciated that although particular systems are separately defined,each or any of the systems can include otherwise combined or separatedvia hardware and/or software. It should also be appreciated thatalthough one suspension member 20 is shown, multiple suspension members20 may be utilized. The suspension member 20 is routed over one or moresheaves 22 thence to a counterweight 24 which may also be disposed inthe hoistway 14. One or more of the sheaves may be a drive sheave 26,operably connected to a machine 28 to control the elevator car 12 alongthe hoistway 14.

The elevator system 10 includes a brake system 30 disposed, in oneembodiment, at the drive sheave 26 to halt rotation of the drive sheave26 and thus stop movement of the elevator car 12 in response to certainselect conditions such as a power failure to the elevator system 10 orother emergency stop (E-stop) situations. While in the describedembodiments the brake system 30 is disposed at the drive sheave 26, itis to be appreciated that in other embodiments the brake system 30 maybe located at the elevator car 12 and is configured to engage the guiderail 16 thus stopping motion of the elevator car 12 in the hoistway 14.

In this embodiment, the brake system 30 is an electromagnetic brake thatis normally in an open position when supplied with electrical power andthe electromagnetic coils thereof are energized. This open positionpermits free travel of the elevator car 12. When, however, the supply ofelectrical power to the electromagnetic coils ceases, the brake system30 engages and safely stops the elevator car 12. In typical elevatorsystems 10, the electromagnetic brake system 30 quickly stops theelevator car 12, but such rapid deceleration of the elevator car 12 mayresult in passenger discomfort.

With reference to FIGS. 2 and 3, two cases during operation of theelevator system 10 where the brake 30 may be applied to stop theelevator car 12 are schematically illustrated. FIG. 2 schematicallyillustrates the case where the elevator car 12 is lighter than thecounterweight and is travelling upward. In this case, when the brakesystem 30 is applied, a brake friction force 32 and a gravity force 34are in opposite directions. This has the effect of lowering adeceleration rate of the elevator car 12. FIG. 3 schematicallyillustrates the case where the elevator car 12 is lighter than thecounterweight and is travelling downward when the brake system 30 isapplied. In this case, the brake friction force 32 and the gravity force34 are in the same direction, effectively increasing the decelerationrate of the elevator car 12 once the brake system 30 is applied. In thiscase it may be desirable to delay application of full brake torque by,in some embodiments, several hundred milliseconds, and soften theapplication of full brake torque to reduce the deceleration rate of theelevator car 12. This also facilitates reduction of the potential forslippage of the suspension member 20.

With reference to FIGS. 4-5, certain regulatory regimes may requireelectro-mechanical brakes to meet the following code requirements:

1—The brake system shall stop the car traveling down with 125% load; and

2—All mechanical components of the brake shall be installed in at leasttwo sets such that if one set fails (N−1), the remainder shall stop andhold the car traveling down with 100% load.

In one embodiment, the brake system 30 includes a multiple ofsequentially operated brake segments 40 a-40 c (three segments shown inthis example). Each brake segment 40 a-40 c is separately operable anddesigned in relationship to the other brake segments to meet the desiredcode requirements. The multiple of sequentially operated brake segments40 a-40 c facilitate emergency stop performance by increasing the timeof which the code required brake torque is applied which, as a result,the deceleration of an E-stop is smoother and more controlled which isparticularly advantageous in territories with frequent powerinterruptions.

In one example elevator system 10, an empty car weighs 1000 kg with aduty load of 2000 kg and a counterweight that weighs 2000 kg at a 0.5overbalance. This results in a potential full car imbalance load of 1000kg and a code requirement of 1500 kg for the 125% load and 1000 kg loadstop for N−1 segments (FIG. 5). In this example, each brake segment 40a, 40 b, 40 c of a 3-segment brake accommodates 500 kg to meet coderequirement 1 of 1500 kg. That is, operation of all brake segments 40 a,40 b, 40 c stop 125% rated load (1500 kg) to meet code requirement 1,while operation of N−1 segments 40 a, 40 b stop 100% load (1000 kg) tomeet code requirement 2. This essentially softens the application offull brake torque to reduce the deceleration rate of the elevator car12. This advantageously compares to a two-segment brake in which each ofthe two segments must provide 100% of the rated load (1000 kg) to meetcode requirement 2 and thus results in a total brake torque of 2000 kgwhen both segments are operational. In other words, code requirement 2for a two-segment brake results in a relatively high rate ofdeceleration during an emergency stop event when both segments areproperly operational—which is typical. Notably, for a 4-segment and5-segment brake, code requirement 1 necessarily controls to meet the125% rated load requirement (1500 kg) (FIG. 5).

With continued reference to FIG. 4, each of the multiple of sequentiallyoperated brake segments 40 a-40 c includes a separately operableelectromagnetic coil 50 a-50 n that drives an associated brake caliper52 a-52 c to control the timing and rate of the brake torque applied toa single brake disc 54. That is, each brake caliper 52 a-52 c isnon-circular and interacts with a respective sector of the single brakedisc 54. Each electromagnetic coil 50 a-50 c may be oval, curved,bean-shaped, circular, etc., and operates to control its respectivebrake caliper 52 a-52 c.

With reference to FIG. 6, each of the multiple of sequentially operatedbrake segments 40 a-40 c (three segments shown in this example) mayalternatively include separate brake subsystems 42 a-42 c. Each separatebrake subsystems 42 a-42 c include a brake disc 44 a-44 c, anelectromagnetic coil 46 a-46 c, and an associated brake caliper 48 a-48c. That is, each brake subsystems 42 a-42 c is self contained andseparately mounted along an axis A on the drive sheave 26.

With reference to FIG. 7, another embodiment of the brake system 30includes three sequentially operated brake segments 60 a-60 c that eachinclude a separately operable electromagnetic coil 62 a-62 c(illustrated schematically) that drives an associated brake caliper 64a-64 c to control the timing and rate of the brake torque applied to asingle brake disc 66. In this embodiment, each brake segment 60 a-60 cis about equivalent in size, while each electromagnetic coil 62 a-62 cis different so as to vary the response time of the three sequentiallyoperated brake segments 60 a-60 c. That is, each brake segments 60 a-60c applies about equal brake torque but is released at a different timefrom the emergency stop (E-stop) initiation. The difference in theelectromagnetic coil 62 a-62 c may be achieved by, for example,different characteristics in the coil design such as a number of coilturns, coil diameter, coil material, coil size, gap size, brakevoltages, plate/housing materials, and/or combinations thereof. Itshould be appreciated that various characteristics may be defined todifferentiate operation of the electromagnetic coil 62 a-62 c.

In this embodiment, the first brake segment 60 a drops relativelyrapidly which almost immediately results in the rapid application ofabout ⅓ of the total brake torque. This rapid application of about ⅓ ofthe total brake torque prevents an over-speed condition (FIG. 7). Then,the second and third electromagnetic coils 62 b, 62 c are sized tosequentially release the associated brake segments 60 b, 60 c tocomplete a relatively smooth stop.

With reference to FIG. 8, upon initiation of an emergency stop (E-stop)operation, the first brake segment 60 a rapidly releases to preventover-speed. Notably, the velocity of the elevator car 12 slightlyincreases but an over speed condition does not occur due to the rapiddrop off of the first electromagnetic coil 62 a. Then, the second andthird electromagnetic coils 62 b, 62 c drop sequentially thereafter toextend the brake activation time to achieve a relatively smooth stop.This sequential operation facilitates passive reduction to otherwiserelatively harsh E-stops, complies with elevator codes, and requires nosupplemental external power.

With reference to FIG. 9, another embodiment of the brake system 30includes an auxiliary brake segment 80 a and two main brake segments 80b, 80 c that each include a separately operable electromagnetic coil 82a-82 c and an associated brake caliper 84 a-84 c to control the timingand rate of the brake torque application to a single brake disc 86. Inthis embodiment, the auxiliary brake segment 80 a is significantlysmaller than that of the main brake segments 80 b, 80 c. In thisexample, the auxiliary brake segment 80 a is an about 30 degree segment,and each of the main brake segment 80 b, 80 c are about 115 degrees. Theauxiliary brake segment 80 a may be sized just large enough to preventan over speed condition. The over speed condition in one example isabout 15% of a nominal e.g. 1 meter per second nominal speed.

With reference to FIG. 10, upon initiation of an emergency stop (E-stop)operation, the auxiliary brake segment 80 a relatively rapidly applies abrake torque sufficient to prevent over-speed. Notably, the velocity ofthe elevator car 12 may slightly increase but an over speed issue doesnot occur due to the rapid application of the auxiliary brake segment 80a. Then, the second and third brake segments 80 b, 80 c drop essentiallysimultaneously thereafter to achieve a relatively smooth stop ascompared to a conventional E-stop. This operation addresses local codechallenges to a sequential brake drop (FIGS. 7 and 8) yet stillfacilitates passive reduction to otherwise relatively harsh E-stops.

With reference to FIG. 11, another embodiment of the brake system 30includes a brake control circuit 100 to control operation of each of amultiple of brake segments 110 a-110 c (three segments shown in thisexample) of the brake system 30 and thereby passively sequence the brakedrop of each brake segment 110 a-110 c to slow the deceleration rate inan E-stop event. Various regulatory agencies require electromechanicalbrake systems to become effective without supplementary delay afteropening the brake release circuit. Diode and capacitor elements are notconsidered by the regulatory agencies to constitute a supplementaldelay.

The brake control circuit 100 includes an electromagnetic coil 112 a-112c, a snubber network 114 a-114 c, and a latching relay 116 a-116 c foreach respective brake segment 110 a-110 c. It should be appreciated thatalthough three segments are illustrated in this example, any number ofsegments will benefit herefrom.

The snubber networks 114 a-114 c are electrically arranged so that theelectromagnetic coils 112 a-112 c are sequenced in time to slow adeceleration rate for an E-stop event. For example, the snubber network114 a may include a surge absorbing component 116, such a Zener diode, aMetal Oxide Varistor (MOV) a Transorb, or other component in series withanother diode 118 for relatively fast operation for the electromagneticcoil 112 a of the brake segment 110 a; the snubber network 114 b may bea resistor 120 in series with a diode 122 for the next sequentialoperation of the second electromagnetic coil 112 b of the second brakesegment 110 b; and the snubber network 114 c may include a capacitor 124in parallel with a diode 126 for the next sequential operation of thethird electromagnetic coil 112 c of the third brake segment 110 c.

Upon initiation of an E-stop operation after loss of power, the snubbernetwork 114 a minimally prolongs current flow for relatively fastoperation of the electromagnetic coil 112 a of the brake segment 110 a.The brake segment 110 a thereby readily rapidly applies a brake torquesufficient to prevent over-speed. Then, the second and thirdelectromagnetic coils 112 b, 112 c drop in accordance with the brakedrop time provided by the respective snubber networks 114 b, 114 c, tocomplete a relatively smooth E-stop. This operation addresses local codechallenges of a sequential brake drop yet still facilitates passivereduction to otherwise relatively harsh E-stops.

It should be appreciated that the snubber networks 114 ab, 114 c may bereadily defined to provide the desired response for each brake segment110 a-110 c. Alternative embodiments of the snubber networks areschematically illustrated in FIGS. 12-16 to provide a range of brakedrop times such as a relatively fast Zener diode snubber networkarrangement (FIG. 12); an adjustable speed snubber network arrangementwith a variable resistor (FIG. 13); a slow snubber network arrangement(FIG. 14); an ultra slow snubber network arrangement with a capacitorand diode in parallel (FIG. 15); and an ultra slow snubber networkarrangement with a diode and a coil or inductor in series (FIG. 16). Itshould be appreciated that various snubber networks, and variouscombinations thereof may be utilized to control the actuation sequenceof each brake segment 110 a-110 c.

The latching relay 116 a-116 c of each brake segment 110 a-110 c may besimultaneously closed in an E-stop event such that a sequential brakedrop of all brake segments occurs. Alternatively, only one or more thelatching relay 116 a-116 c are closed such that the particular latchingrelay 116 a-116 c are set to a selected position at a beginning of anelevator car 12 run, based on, for example, a direction of elevator car12 travel such as regen or motoring, and/or load imbalance between theelevator car 12 and the counterweight 24. That is, only particular brakesegments 110 a-110 c may be set for a particular elevator run. While thelatching relays 116 a-116 c are illustrated and described herein, it isto be appreciated that other switching mechanisms may be utilized in thebrake control circuit 100. For example, in other embodiments a normal,non-latching relay or an electronic switch such as a mofset may be used.Further, an additional relay may be utilized in conjunction with themofset to “latch” the mofset. This operation addresses local codechallenges of a sequential brake drop yet still facilitates passivereduction to otherwise relatively harsh E-stops.

The use of the terms “a,” “an,” “the,” and similar references in thecontext of description (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or specifically contradicted bycontext. The modifier “about” used in connection with a quantity isinclusive of the stated value and has the meaning dictated by thecontext (e.g., it includes the degree of error associated withmeasurement of the particular quantity). All ranges disclosed herein areinclusive of the endpoints, and the endpoints are independentlycombinable with each other.

Although the different non-limiting embodiments have specificillustrated components, the embodiments of this invention are notlimited to those particular combinations. It is possible to use some ofthe components or features from any of the non-limiting embodiments incombination with features or components from any of the othernon-limiting embodiments.

It should be appreciated that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould also be appreciated that although a particular componentarrangement is disclosed in the illustrated embodiment, otherarrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, itshould be understood that steps may be performed in any order, separatedor combined unless otherwise indicated and will still benefit from thepresent disclosure.

The foregoing description is exemplary rather than defined by thelimitations within. Various non-limiting embodiments are disclosedherein, however, one of ordinary skill in the art would recognize thatvarious modifications and variations in light of the above teachingswill fall within the scope of the appended claims. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced other than as specifically described. For that reasonthe appended claims should be studied to determine true scope andcontent.

What is claimed is:
 1. A brake system for an elevator car comprising: amultiple of sequentially operated brake segments to control a timing anda rate of brake torque for deceleration of the elevator car uponinitiation of an E-stop operation after loss of power, wherein themultiple of sequentially operated brake segments include at least threebrake segments, wherein each of the multiple of sequentially operatedbrake segments includes an electromagnetic coil that controls the timingand the rate of brake torque for that brake segment; and a brake controlcircuit operable to control operation of each of the multiple of brakesegments to passively sequence activation of each of the multiple ofbrake segments, wherein controlling a response time of each of themultiple of brake segments is effectuated by a snubber network, themultiple of sequentially operated brake segments operable to stop 125%of a rated load of the elevator car, an N−1 number of the multiple ofsequentially operated brake segments operable to stop 100% of the ratedload of the elevator car wherein N is the total number of brakesegments.
 2. The system as recited in claim 1, wherein the brake controlcircuit includes an electromagnetic coil and a snubber network for eachof the multiple of brake segments.
 3. The system as recited in claim 2,wherein the snubber network for each of the multiple of brake segmentscontrol a sequence to control the deceleration of the elevator car. 4.The system as recited in claim 1, wherein the snubber network includes adiode.
 5. The system as recited in claim 1, wherein the snubber networkincludes a Zener diode.
 6. The system as recited in claim 1, wherein thesnubber network includes a resistor in series with a diode.
 7. Thesystem as recited in claim 1, wherein the snubber network includes acapacitor in parallel with a diode.
 8. The system as recited in claim 1,wherein the snubber network includes a coil in series with a diode.
 9. Abrake system for an elevator car upon initiation of an E-stop operationafter loss of power, comprising: a first brake segment operable to applya first brake torque at a first time in response to a first snubbernetwork; a second brake segment sequentially operable subsequent to thefirst brake segment in response to a second snubber network, the secondbrake segment operable to apply a second brake torque at a second timesubsequent to the first time; and a third brake segment sequentiallyoperable subsequent to the second brake segment in response to a thirdsnubber network, the third brake segment operable to apply a third braketorque at a third time, wherein controlling the response time of each ofthe multiple of brake segments is effectuated by a snubber network, themultiple of sequentially operated brake segments operable to stop 125%of a rated load of the elevator car, two of the multiple of sequentiallyoperated brake segments, operable to stop 100% of the rated load of theelevator car.
 10. The system as recited in claim 9, wherein the thirdtime is subsequent to the second time.
 11. The system as recited inclaim 9, wherein the third time is about equal to the second time.
 12. Amethod of engaging an electromagnetic brake for an elevator system uponinitiation of an E-stop operation after loss of power, comprising:sequentially controlling application of a multiple of brake segments fordeceleration of the elevator car in response to the stopping of a flowof electrical current through a passive brake control circuit whereincontrolling the response time of each of the multiple of brake segmentsis effectuated by a snubber network, each of the multiple ofsequentially operated brake segments includes an electromagnetic coilthat controls the timing and the rate of brake torque for that brakesegment, the multiple of sequentially operated brake segments operableto stop 125% of a rated load of the elevator car, an N−1 number of themultiple of sequentially operated brake segments, operable to stop 100%of the rated load of the elevator car wherein N is the total number ofbrake segments.
 13. The method as recited in claim 12, whereinsequentially controlling application of each of the multiple of brakesegments includes controlling a response time of each of the multiple ofbrake segments.
 14. The method as recited in claim 13, wherein the brakecontrol circuit includes an electromagnetic coil and a snubber networkfor each of the multiple of brake segments.
 15. The method as recited inclaim 14, wherein the response time of each of the multiple of brakesegments is determined by the snubber network.
 16. The method as recitedin claim 12, wherein upon initiation of an E-stop operation after lossof power, the snubber network prolongs current flow for relatively fastoperation of a first brake segment sufficient to prevent over-speed. 17.The method as recited in claim 16, wherein a second and thirdelectromagnetic coils of a second and third brake segment operate inresponse to a brake drop time provided by the respective first andsecond snubber networks, to complete the E-stop.